This invention relates to a fuel system, and particularly to a fuel-delivery control system. More particularly, this invention relates to a filler neck and a valve assembly for regulating flow of liquid fuel and fuel vapor through a fuel tank filler neck.
A filler neck is a tube which conducts liquid fuel from a fuel-dispensing pump nozzle to an interior fuel storage region in a fuel tank. Although an open passageway through the filler neck into the fuel tank is needed during refueling to conduct liquid fuel from a pump nozzle into the fuel tank, it is desirable to close the filler neck at all other times to block discharge of liquid fuel and fuel vapor from the fuel tank through the filler neck. In many cases, a fuel cap is mounted on an outer end of the filler neck to close the filler neck during the time period before and after each tank refueling activity.
It is also known to use a check valve with a fuel tank inlet neck to close the filler neck under certain circumstances. Typically, such a check valve, where used, has been a swinging trap door or a floating ping-pong ball in a cage. The disadvantage of these systems is that, when located at or below liquid level in the fuel tank, it is difficult to initiate fuel fill into the fuel tank since the existing fuel in the fuel tank must be displaced for the check valve to open.
What is needed is a fuel-delivery control system apart from a cap that can automatically close a passageway through a filler neck under normal conditions and open the filler neck passageway during refueling. Ideally such a system would be designed to maximize the flow rate of liquid fuel into the fuel tank during refueling without creating a lot of unwanted fuel vapor. In addition, such a control system should provide a fast response to close the passageway in the event of a sudden rise in tank pressure, as when the tank achieves a full level. Rapid closure of the passageway prevents flow reversal from the tank which can result in "spitback" or the spray of fuel from the filler neck as the fuel-dispensing pump nozzle shuts off.
According to the present invention, a fuel-delivery control system is provided for regulating flow through a filler neck into a fuel tank. The system includes a housing module formed to include a fuel-delivery channel and a check valve assembly positioned to lie in the fuel-delivery channel.
The check valve assembly includes a support base, a valve member, and a spring. The support base is appended to the housing module. The valve member is coupled to the support base for sliding movement between a channel-closing position engaging the housing module and a channel-opening position disengaging the housing module. The support base and valve member are formed to include a closed interior region therebetween. The spring is positioned to lie in the closed interior region and yieldably urge the valve member toward its channel-closing position.
In preferred embodiments, the support base includes a radially extending mounting fixture appended to an interior wall of the fuel-delivery channel and a conical tail fixed to an axially extending edge of the mounting fixture. The conical tail is arranged to extend along the longitudinal axis of the fuel-delivery channel in spaced-apart relation from the interior wall of the fuel-delivery channel. The support base further includes a cylindrical guide sleeve appended to a circular forward end of the conical tail.
The housing module includes a circular valve seat provided in the fuel-delivery channel. Illustratively, the housing module containing the check valve assembly is mounted adjacent to the fuel tank in an inlet throat tube appended to the fuel tank.
In a first embodiment, the valve member includes a dome-shaped closure member facing toward the circular valve seat and a slidable guide stem extending into the cylindrical guide sleeve included in the support base. Illustratively, the spring is placed in an interior space formed inside the guide sleeve of the support base and the guide stem of the valve member. The spring is a compression spring that normally acts, at all times other than refueling, to exert a biasing force against the dome-shaped closure member so that it sealingly engages the circular valve seat formed in the fuel-delivery channel to block flow of liquid fuel and fuel vapor through the fuel-delivery channel.
In a second embodiment, the valve member includes a base portion, an annular seal member, and a somewhat conical nose portion. When the valve member is moved by the spring to its fuel-delivery closing position, the annular seal member sealingly engages the circular valve seat formed in the housing module.
In a third embodiment, the length of the tail in the support base and the length of the valve member are shortened as compared to other embodiments to produce a smaller, more compact check valve assembly. At the same time, the length of the housing module containing the check valve assembly is also minimized.
A filler neck is used to conduct liquid fuel from a filling station pump nozzle to the fuel tank. An outer end of the filler neck carries a removable fuel cap and an inner end of the filler neck is connected to the housing module so that liquid fuel conducted through the filler neck will pass through the fuel-delivery channel formed in the housing module on its way into the fuel tank. The check valve assembly lies in that fuel-delivery channel and functions to regulate flow of liquid fuel and fuel vapor between the filler neck and the fuel tank.
During refueling, liquid fuel discharged by a pump nozzle into the filler neck operates to move the valve member automatically to its fuel-delivery channel-opening position in the following manner. Liquid fuel passes through the filler neck on its way toward the fuel tank, strikes the component (e.g., either the dome-shaped closure or the conical nose portion and annular seal member) that is in engagement with the circular valve seat provided in the fuel-delivery channel, and urges the valve member in an axially inward direction against its biasing spring and away from the circular valve seat provided in the fuel-delivery channel. This movement creates an annular fluid-conducting space around the dome-shaped closure or conical nose portion so that liquid fuel dispensed by the pump nozzle can pass around the valve member and support member and through the fuel-delivery channel into the fuel tank.
The check valve assembly is designed and configured to control flow of liquid fuel and fuel vapor through the fuel-delivery channel without causing the flow of liquid fuel passing around the movable member and fixed support member to become turbulent when the valve member is moved to its fuel-delivery channel-opening position during refueling. Turbulent liquid fuel flow creates unwanted fuel vapor and also creates unwanted back pressure in the fuel tank that might lead to premature shutoff of the filling station pump nozzle. Advantageously, the flow annulus around the valve member is only slightly larger than the inlet passage of the fuel-delivery channel and the check valve assembly elements are tapered, contoured, and arranged to minimize turbulent flow of liquid fuel during refueling.
In addition, an exhaust passage is provided to discharge air or fuel vapor from interior space receiving the spring and lying between the support base and the valve member to an exit portion of the support member. This exhaust passage functions to exhaust air or fuel vapor from the spring-receiving interior space during rapid opening of the valve and to allow fuel tank pressure to assist the spring in valve closure when tank pressure increases suddenly.
Additional objects, features, and advantages of the invention will become apparent to those skilled in the art upon consideration of the following detailed description of preferred embodiments exemplifying the best mode of carrying out the invention as presently perceived.